Eat to live and not live to eat

For the last 2 months, I've been surviving on low salt,low protein, low phosphorus and low potassium meals (except for the occasional restaurant food like the mini Japanese curry rice), I've lost 4 kg of body weight. I am on the above special meals not to lose weight but due to my low kidney filtration rate or GFR of 54.
In my next medical checkup, I hope to see my GFR going up, say to 60+